Not sure on that one Rick. I had to do alot of reading to see what parts were correct on mine.
My first thought on the 205 from a Ford is the output locations.
I would think the ford 205 has the front output on the driver side, opposite from a chevy version passenger side drop. Maybe it could be mounted upside down with a cable shifter....but Its pretty easy and inexpensive to just find the chevy 205 somewhere and probably worth all the savings in fabrication, working out kinks, and headaches.
As far as the 203 goes, any of them from a GM will work as long as the adapter plate you use is correct for your tranny....a th350 has a 27 spline male output and the adapter has a female 27 sleeve that couples them. A Th400 has a 32 spline female output etc.
If you go looking for a chevy 205 to do a doubler....make sure you get one with a 32 SPLINE female input. All the adapters ive seen require this version. you can change a 27 spline 205 from a 1/2 ton into 32 spline from a 1 ton if you change the shaft and mill out the case for the 3/8" larger bearing it takes.
Good luck - its a fun process and im glad mines almost over.
